1. Field of the Invention
The present invention relates to methods of and apparatus for forming conductive patterns on a substrate.
2. Description of the Prior Art
It has been proposed to produce conductive strips on a substrate to form connections between integrated circuits. Such conductive strips are of low cost metals such as copper and tin and are formed on a ceramic substrate or a multi-layered substrate including glass or glass-ceramic materials. One process for forming such conductors is to etch a solid film of conductor formed on a substrate. With such etching techniques, however, the etching fluid tends to undercut the conductors and so there is a limit to the width to which such conductors can in practice be formed. Also etching techniques are wasteful of materials and disposal of the waste products can be difficult.
Another method of forming conductors is to screen print the conductors on the substrate. In practice, however, the resolution of screen printing is limited and so again this places a limit on the width of and spacing between the conductors which can be formed on a substrate.
A still further method of forming conductors on a substrate is by means of an additive method using a plating or lift-off evaporation process. Again in practice such techniques either require the extensive use of aqueous processes, which is undesirable, or require high cost equipment to achieve high accuracy.
It is an object of the invention to provide a high resolution method of forming a conductive pattern on a substrate.